Due to their unique properties and diversity, two-dimensional (2D) nanomaterials have attracted tremendous interest from the scientific community in recent years, especially for energy storage applications. Herein, we present a strategy to prepare flexible and conductive MXene/graphene (reduced graphene oxide, rGO) supercapacitor electrodes by using electrostatic self-assembly between positively charged rGO with poly(diallyldimethylammonium chloride) and negatively charged MXene nanosheets. After electrostatic assembly, rGO nanosheets are inserted in-between MXene layers. As a result, the self-restacking of MXene nanosheets is effectively prevented, leading to a considerably increased interlayer spacing. Accelerated diffusion of electrolyte ions enables more electroactive sites to become accessible. The as-prepared freestanding MXene/rGO-5wt% electrode displays a volumetric capacitance of 1040 F cm -3 at a scan rate of 2 mV s -1 and anThis article is protected by copyright. All rights reserved.3 impressive rate capability with 61% capacitance retention at 1 V s -1 . Moreover, the film electrode exhibits long cycle life with almost no capacitance decay after 20,000 cycles. More importantly, our binder-free, symmetric supercapacitor fabricated with MXene/rGO-5wt%shows a maximum volumetric energy density of 34.6 Wh L -1 and an ultrahigh volumetric power density up to 74.4 kW L -1 , which is among the highest values reported for carbon and MXene based materials in aqueous electrolytes. This work not only provides fundamental insight into the effect of interlayer spacing on the electrochemical performance of 2D hybrid materials, but also sheds light on the design of next-generation flexible, portable and highly integrated supercapacitors with high volumetric and rate performances.